In the field of lightweight beam construction, deflection of the beam tends to increase as the length of the span increases. In a freestanding display such as those commonly used for presentations, it is important that the frame supporting a display board be light enough to allow some degree of portability of the display. Achievement of the desired lightness can be achieved in part by the use of lightweight materials, such as aluminum, in the frame construction, and also through the use of box beams. The corollary to increased conservation of weight, however, is that the strength of the beam is, as a general rule, reduced. On the other hand, an increase in the strength of the beam usually results in a rather substantial increase in the cost of its manufacture.
For example, it is well known that extruded aluminum parts can be utilized in many instances to form structural beams which would be substantially lighter than corresponding steal beams, and yet would exhibit sufficient strength to form, for example, the frame for supporting a display board or the like. However, to extrude such a beam for large spans (say in the range of 6 to 10 feet with a cross section of approximately 6".times.4") it would be necessary that the wall thickness of the extruded part be at least approximately 0.186".
Applicants, however, in an effort to reduce even further the weight and the cost of such a beam, have discovered a novel composite and/or modular aluminum extrusion beam which can be made substantially lighter and more inexpensively than beams of the type heretofore employed for constructing frames for display boards and the like.
In view of the foregoing, it can be seen that there is a need for an inexpensive, lightweight composite beam construction as herein described which will prevent any undesirable sagging of the beam over extended lengths thereof, and will thereby increase the stability of any freestanding display stands made therefrom, and thus will maintain the integrity and appearance of the freestanding display.